The field of the invention relates generally to electric machines, and more specifically, to an interior permanent magnet rotor for use in an electric machine and methods of assembling the same.
Various types of electric machines include permanent magnets. For example, a direct current (DC) motor may include a plurality of permanent magnets coupled to an exterior surface of a rotor core. Typically, the plurality of permanent magnets are coupled to the exterior surface of the rotor core using an adhesive and/or a retaining ring. The plurality of permanent magnets must be coupled to the rotor core such that the permanent magnets remain coupled to the rotor core even when high speed rotation of the rotor exerts forces on the permanent magnets tending to separate the permanent magnets from the rotor core.
Permanent magnets may also be positioned within a rotor core. Such a rotor may be referred to as an interior permanent magnet rotor. Typically, magnets have been retained within the rotor core by riveting end laminations without openings to the rotor core. End laminations may also be coupled to the rotor core, after the permanent magnets are positioned within the rotor core, by welding, staking, or adhesives.